Kinetics of theta-positive and theta-negative lymphocytes in thymus-deprived and normal mice. An autoradiographic study.

Life spans and proliferative kinetics of theta-positive (theta +) and theta-negative (theta -) cells were evaluated in normal, neonatally thymectomized (NeoTx) and sham-thymectomized (ShamTx) Balb/c mice. This was done by exposing cell suspensions, incubated with anti-theta antiserum + complement, to a dye exclusion test followed by fixation and autoradiography. Results from normal mice given [3H]thymidine injections 5 weeks before being killed indicated that long-lived theta + and theta - cells constituted about equal percentages of the respective populations in peripheral lymphoid tissues. Long-lived theta + cells constituted a relatively high percentage of theta + cells in the bone marrow, whereas a minority of the theta - lymphocytes were long-lived. Results from NeoTx and ShamTx mice, given intensive injections of [3H]thymidine, showed that the theta - cells of the mesenteric nodes were renewed at comparable rates in both groups of mice, whereas the theta + cells were more rapidly renewed in NeoTx mice than in sham-operated littermates. In the bone marrow, the majority of both theta - and theta + cells were very rapidly renewed, indicating a production of these cells in the bone marrow of Sham Tx mice and also in NeoTx mice, in which the number of bone-marrow theta + cells was significantly higher than in Sham Tx littermates.